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Ian's Introductory Note: this is a very interesting article on Indy for many reasons: it shows just how advanced the system was for its time with respect to as-standard features and level of integration, as well as how cheap it was compared to equipping a PC with the same features back then (such as ISDN and full stereo audio), even though the absolute prices at the time seem high now. However, as an indicator of what a typical 2nd-hand Indy system might be like today, it is distinctly inaccurate: 'typical' processor types and sizes of disk, monitor and RAM will be better than was present in the machine reviewed by PCW in 1993. For a complete insight into these issues, read the review below, and then browse through my page on 2nd-hand purchasing advice for Indy.

Silicon Graphics Indy

PCW, September 1993

(Historical Article)

[SGI Indy] Personal computers are getting increasingly fast, powerful and easy on the budget. Simon Rockman got to grips with a prototype Indy, Silicon Graphics' featured-packed Unix-based box for traditional computer-aided markets.

Most computers go through a natural cycle of being jolly whizzy when launched and useful workhorses in middle age before being superseded by something better, cheaper and faster. At under 5000 UKP Silicon Graphics' Indy is cheaper and, in most important respects, better than the R3000 Indigo which will set you back 8000 UKP.

Silicon Graphics has ventured into budget computing before, but at that time the company wrongly claimed that the original Indigo was a sensible alternative to a PC. No such claims are being made for the Indy. Despite the Temple of Doom moniker, this is not a product that explores untapped markets, but is designed to broaden the horizons of the existing user base. This is a Unix box aimed at the traditional markets of computer-aided chemistry, design and engineering. Silicon Graphics speaks of breaking into the publishing market with products like Photoshop, and the existing machines do have quite a following in the computer graphics field - both strong markets for high-end Macs.

Silicon Graphics claims that Unix is for the ordinary user, and with the inclusion of a new graphical user interface, called Indigo Magic, there is some truth in that. The Indy is cheap; not as cheap as a dodgy 486 clone, but well-priced and powerful. For 4350 UKP you get a 15in monitor, 256 colour video and 16MB RAM, It will need a SCSI-2 hard disk, which is likely to set you back a good 500 UKP for anything decent, and perhaps the same again for a tape drive, so the cost soon builds up. Silicon Graphics will sell you a system with a hard disk for 6000 UKP. The paperwork claims a 340MB SCSI disk, and the nice man from Silicon Graphics says 500MB, but either way 1600 UKP is steep for a moderate-size hard disk. Apparently, that's just the way Unix systems are. The operating system comes on CD-ROM so you can buy a machine and fit your own hard drive, but you will then need to configure it yourself and buy a CD-ROM drive.

[Inside the Indy]

The 6000 UKP price tag is pre-haggle, so expect a little movement if you are buying a network. You get, or will get, a particularly stylish machine for your money. The prototype I looked at was a raw chassis, since the plastic casing was stuck in customs at Charles De Gaulle airport. When assembled, the machine will have a graphite-coloured monitor and keyboard to co-ordinate with the camera pictured opposite, and the machine itself is a smart blue. The low profile 'pizza box' shape is now quite common among workstations, and the 76.2mm x 406.4mm x 355.6mm Indy looks substantial by comparison. Yet for something which packs so much power, it is amazingly sleek.

Use of MIPS processors

Two versions of the Indy are available, both with 100MHz MIPS R4000 processors, but one adds a 512K secondary cache to the system. Silicon Graphics bought MIPS a little over a year ago and is firmly tied to this range of RISC processors, but this does not impinge on the use of MIPS processors in other manufacturers' machines. Both DEC and Olivetti build MIPS boxes.

The Indy is designed to be a low-cost 64-bit system. While Pentium-powered machines are 64-bit up to the secondary cache, they tend not to carry that through to the rest of the system. This severely affects the throughput of the machine, but keeps down the cost of manufacture for companies geared to producing traditional PCs. Silicon Graphics is unlikely to use any of the other MIPS processors in the Indy for the short term. The R3000 only has a 32-bit bus and is primarily used for control applications; the R4400, the more powerful version of the R4000, is still too expensive, and the R4200, the low-power cheap chip, is still on the drawing board.

The Indy is supplied as standard with 16MB RAM, expandable on the motherboard to 256MB. The motherboard clock is asynchronous from the CPU and runs at 50MHz, giving a throughput of 400MB/sec when accessing RAM and 267MB/sec to the rest of the bus. This compares with a good PC offering 80MB/sec. Throughput is further aided by a 10MB/sec SCSI-2 port.

The processing power runs a close match to the Pentium. It is dangerous to quote the same benchmark for rival processors, but using SPEC statistics supplied by Intel and MIPS, the integer maths figure for the secondary cache R4000 is 57 to the Pentium's 64, and the floating point figure is 61 to the Pentium's 55. Bear in mind that floating point is the Pentium's biggest area of improvement and you can see that the R4000 leaves the 486 standing. These Pentium figures are for the 66MHz version which is still a few months off - it should be available around the same time as the Indy. In the graphics rendering market SGI sees high-end Macs as a rival, but claims 40 times the performance of a machine with a 68030.

Graphics performance

Silicon Graphics has always offered impressive graphics performance. The Indy is aimed at users of 2D packages: for 3D work, the graphics performance of an uprated Elan Indigo will outstrip it. Using graphics users' standard benchmarks, the Indy with the 1MB secondary cache will produce between 1.2 and 1.4 million X lines per second, 700,000 2D vectors per second, and 480,000 3D vectors per second. Without secondary cache, performance is about three quarters of this. With a blit rate of up to 40 million pixels per second, SGI claims that Indy is the highest-performing desktop. All these graphics use the standard 8-bit mode but a 24-bit card is available as an option. The standard 15in Trinitron monitor displays images at 1024 x 768 but there is a 1280 x 1024 option if you buy a 16 or 17in monitor.

Indy doesn't just have impressive graphics and processing. A fast CPU and bags of RAM allow for CD-quality sound digitising: there are four analog and two digital channels. The two serial ports double up as Midi ports. The internals are impressive. Two GIO64 slots take a range of SGI cards, and there is space for two one-inch high drives (SGI refers to this as expandable to 2GB). The front of the case is dominated by the processor or, more accurately, by its ceramic heatsink. In the review machine, this covered the cache as well as the processor.

Cooling is a problem, and without the case the lack of airflow to the video subsystems caused a glitch. However, SGI makes much more powerful machines than this, and is more likely to understand the cooling problems of its own chips than the small Pentium-clone builder which cannot draw on experience.

[there is a picture of the IndyCam at this, but it's a poor image; I shall include my own clearer picture soon]

Desktop video conferencing hasn't yet made its mark, but the Indy aims to make a dent in this fledgling market by including the IndyCam as standard.

To motor racing aficionados an IndyCam is a television camera tounted on the type of racing car Nigel Mansell is driving this year. To Silicon Graphics, an IndyCam is a television camera which sits on top of the monitor looking like a baddie robot in RoboCop 2.

This camera digitises a 640 x 480 image in 24-bit colour at a rate of 30 frames per second directly into system memory. Similar real-time PC solutions need an external frame buffer. The machine is supplied with a video-enabled version of Z-mail, so as well as being able to send messages to colleagues, you can see and hear them. This may sound gimmicky but is genuinely useful when combined with the digital whiteboard to show your plans. Computer animators often work in teams and need to show how objects will interact, so this has practical uses beyond playing noughts and crosses with someone on another floor.

Z-mail only runs a 132 x 120 window at 10 frames per second to keep the usage down to around 4 percent of the Ethernet bandwidth.

This is a bit jerky, but at least you can recognise the person at the other end and tell if they are smiling, which is far better than BT's dreadful videophones. Besides, once you have seen one computer graphics engineer and his ponytail, you've pretty much seen them all. Up to 20 users can talk to each other, so it's good for conferences.

IndyCam uses a CCD (charge coupled device) camera. The electronics within the camera bit and the fixed focus wide angle lens are all quite cheap components. It relies on the power of the machine to work, and produces good results without costing a fortune.

Video cards

The review machine was fitted with two video cards like layer cakes. One card offered full 24-bit video, and the second, real-time video manipulation, to allow video to be printed straight to tape in PAL or NTSC formats. The main video-in processor was missing from the test machine but will be surface-mounted in all Indys from the ship date. Two large ASICs (application specific integrated circuits) provide multiplexing to separate the processor bus from the standard GIO64 bus. They also provide two-way memory interleaving - part of the reason for the good memory data throughput. This is aided by the custom memory controller ASIC which allows DMA from RAM with a very low CPU overhead. As a high-spec machine the review unit was fitted with a 20MB 3.5 in floptical drive. This not only gives high-capacity floppies at a higher speed than conventional drives, but flopticals look likely to kill off the 2.88MB format which has failed to gain any ground.

[Outside the Indy]

Without a CD-ROM drive the operating system has to be loaded over the network. This is no problem - the Indy is well connected. There are AUI and 10BaseT Ethernet ports (you need an external transceiver to plug in any Ethernet cable). The comprehensive connections beyond this fill the back of the machine. PC users will recognise the mouse and keyboard connectors, the bi-directional parallel port, and two serial ports which double as Midi in and out. The monitor connecter is a large D-type and the SCSI-2 port a standard 50-way connecter.

The video side is more exciting, with digital video in, S-video in, composite NTSC/PAL video in and the optional composite NTSC/PAL video in/out in one of the slots.

Video is matched by the audio side which has microphone, headphone, and digital audio in and out. Two unusual options are the 3D glasses connecter and the ISDN port.

Thanks to a BT initiative, ISDN is now widespread and cheap, Installation costs around 400 UKP and provides you with two 64kbps lines. This is not very much more than conventional business lines and provides a much higher throughput, but the cost of ISDN terminal adapters typically well over 1000 makes the start-up cost of at least 3000 point to point a lot less attractive. Building ISDN into the machine changes the economics substantially.

The 3D glasses use an LCD shutter. The screen displays the image for the right eye and the glasses make the left lens opaque. On the next screen refresh, the screen shows the left eye and the right lens is switched to be opaque with the left lens cleared. The effect is to give real perspective to an image, and needs a high refresh rate to reduce interlace flicker. The technology is simple and has been used in computer games to give a Victorian duoscope-type effect.

With advanced 3D modelling it is possible to give real depth, but the need to refresh the entire display at least 30 times per second on a machine with a large operating system requires a frame buffer and a lot of processor power, as well as good data throughput. The major market for this software is computer-aided chemistry, and since it only requires a minimal amount of circuitry and a socket to add the feature to the Indy, it is a worthwhile addition.


The camera, high-quality graphics and Photo CD option, along with the speech and music features, need software support. SGI supplies this in a new X-Windows based front end called Indigo Magic. As you would expect, this is a WIMPs program with drag and drop for printing, for example. Features include 'drop pockets', which store windows like names in an address book, and a 'shelf' which aliases programs in one window with an icon in another, in a similar way to the Apple System 7.0 alias command.

The Iris Showcase presentation graphics program has been upgraded. The new version 3.0 allows you to create interactive documents which combine audio, video, 2D and 3D graphics. SGI calls this Digital Media.

Indigo Magic will migrate to other Silicon Graphics machines but at first will only be available with the Indy. It allows a number of users to customise individual desktops and save them as an icon. As an incentive to get to grips with Indigo Magic, the Indy comes with a free games CD.

What Indy will not do, initially at least, is run Windows NT. When the Elan was launched, Silicon Graphics billed it as the workstation for the masses. Despite good price/performance against Intel-based machines, it failed to make a mark commercially. Instead, it went into classrooms and helped flesh out networks among existing SGI customers. With that lesson learnt, Indy is now aimed at those traditional markets and they don't want NT.

The marriage of competitive hardware and a mass-market operating system may seem like the ideal setup, but it will still be twice the price of a Windows box and NT still has to prove itself. There will be NT for MIPS, and something like the Indy may be the right machine on which to run it, but Silicon Graphics does not feel it has enough control of the operating system. However close the relationship with Microsoft, it is not the same as having the source code. Silicon Graphics will have to wait for NT drivers for special functions like camera, sound and video hardware, which is a shame, because NT would give access to a large base of affordable programs running in a native mode.

The Indy will run PC and Mac programs in emulation, but the results of emulation are usually unsatisfactory [though a later good CPU such as the R5000 is fine for running SoftWindows].

Silicon Graphics talks about 'the out of box experience' - Californian jargon for making the machine easy to set up and use. A full-motion, one-hour video tutorial teaches you how to use the machine and there is extensive on-line help, but this is still not a machine for an environment with no techies around.


The Indy is a bargain - but only if you need the features. To equip a Pentium PC with CD-quality sound and ISDN would cost roughly twice as much as an Indy. For raw processing it runs neck and neck with a Pentium machine, and as a Unix server it has the proven reliability of the R4000 over the as yet unproved Pentium machines. Once you start using any of the special features, the Indy is an unbeatable platform. Its sound features, or video conferencing or graphics performance alone, put a PC in the shade.

The sticking point is the cost of software. The low volumes in which Unix software sells, and the profile of the customers who buy the packages, makes a workstation too expensive to be a viable alternative in most office applications - a pity, since the hardware is far better. The traditional backwater for such systems is a move into vertical markets, but code compatibility with the earlier Indigo and other Silicon Graphics machines gives the Indy a base of 1300 applications from which to grow. The box is exciting, but what goes on inside is even better.



Silicon Graphics

16MB expandable to 256MB

Mass storage
None as standard. SCSI-2 for seven devices but only two 1in bays

Storage options
Hard disks; floptical and CD recommended

102 keys

Monitor 15in Trinitron, larger options

Display modes
1024 x 768 in 256 colours. Option to 1280 x 1024 in 24-bit colour

Standard interfaces
Parallel, serial, MIDI, ISDN, Ethernet, miscellaneous analog and digital video formats, miscellaneous analog and digital audio formats, SCSI-2

76.2mm x 406.4mm x 355.6mm


Bundled software
Assorted multimedia and presentation graphics tools

Unix [SGI's version which is called IRIX] and Indigo Magic


Late September 1993

Prices [all ancient UKP]

Basic Indy:             4330 + VAT
With 340MB hard disk:   5630
1MB secondary cache
processor card:         2600
CD-ROM drive:            750
Floptical drive:         430
RAM (per MB):             80
24-bit graphics:        2600
Optional video in/out:  3460

Thanks to Gareth Edwards for lending me his copy of the relevant issue of PCW

Ian's SGI Depot: FOR SALE! SGI Systems, Parts, Spares and Upgrades

(check my current auctions!)
[WhatsNew] [P.I.] [Indigo] [Indy] [O2] [Indigo2] [Crimson] [Challenge] [Onyx] [Octane] [Origin] [Onyx2]
[Future Technology Research Index] [SGI Tech/Advice Index] [Nintendo64 Tech Info Index]